Hello!
Based on the Japanese video game series of the same name by Konami, the first two seasons of Castlevania adapt the 1989 entry Castlevania III: Dracula's Curse and follow Trevor Belmont, Alucard and Sypha Belnades as they defend the nation of Wallachia from Dracula and his minions.
In short, when his wife is burned at the stake after being falsely accused of witchcraft, the vampire Count Vlad Dracula Țepeș declares all the people of Wallachia will pay with their lives. He summons an army of demons which overruns the country, causing the people to live lives of fear and distrust. To combat this, the outcast monster hunter Trevor Belmont takes up arms against Dracula's forces, aided by the magician Sypha Belnades and Dracula's dhampir son Alucard.
@criptomaster